Frank Sherwood Rowland:WHAT COULD be the human significance of a scientific paper entitled Stratospheric Sink for Chlorofluoromethanes: Chlorine Atom-Catalysed Destruction of Ozone? As it turns out, a lot. In 1974, F Sherwood "Sherry" Rowland, who has died aged 84, and his co-author Mario Molina, saw that a class of synthetic chemicals already in wide and growing usage around the world could cause pronounced thinning of the Earth's natural ozone layer, thus subjecting life on the planet's surface to larger doses of harmful ultraviolet (UV) rays from the sun.
Their paper in the journal Nature laid out the basic science and the plausibility, if not inevitability, of global impacts of these chlorofluorocarbon (CFC) chemicals and demonstrated how certain human activities can have environmental impacts far beyond what one might intuit. Two decades later, Sherry, Molina and Paul Crutzen shared the Nobel prize for chemistry “for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone”.
By the mid-1970s, CFCs were seen as an industrial success story, first as refrigeration fluids and later as propellants for aerosol-spray products such as deodorants and hairsprays. Invisible and engineered to be chemically inert, these synthetic chemicals were thought to be safe. But Sherry had heard of CFCs being detected in air over the Atlantic by the British scientist James Lovelock and wondered what would eventually happen to them.
Laboratory data convinced him and Molina that the CFCs would be destroyed over the course of about 100 years, only after drifting above most of the ozone layer and encountering harsh UV light that would break them apart into their component atoms: carbon, chlorine and fluorine.
That debris would be the problem. Chlorine atoms released into the ozone layer would initiate chain reactions, Sherry realised. They calculated that much of the ozone layer could be destroyed if CFC usage grew. That ozone shields the Earth from biologically damaging UV was already known in 1974. UV’s role in inducing some skin cancers in humans was an example.
He pressed his case. Opposition from affected industries arose and he was criticised, ridiculed and discounted. One industry group called him an agent of the KGB. But he persisted and an international agreement, the Montreal Protocol, was enacted in 1987 to limit the production and release of CFCs. The unexpected discovery in 1985 of the Antarctic ozone hole by the British Antarctic Survey, confirmed within months by Nasa, had added some drama behind the scenes, while Antarctic fieldwork by teams of scientists confirmed that chlorine’s attack on ozone was causing the hole.
Throughout the 1970s and 1980s, Sherry spoke so clearly and forcefully that public opinion turned against CFCs. Consumption decreased in the US and American chemical firms began to seek alternative, ozone-safer chemicals.
With his colleague (and former student) Don Blake, Sherry reported exacting measurements in 1982 showing that the greenhouse gas methane was growing in concentration in air samples from all over the world. This finding attracted much attention and demonstrated that human-caused climate change can extend beyond carbon dioxide released from burning fossil fuels. The second of three sons, Sherry was born in Delaware, Ohio. He studied at Ohio Wesleyan University and at Chicago University, then became instructor in chemistry at Princeton University. After an assistant professorship at the University of Kansas, he was made professor of chemistry at the University of California, Irvine. He was elected to the US National Academy of Sciences (1978) and was made a foreign fellow of the Royal Society (2004).
His exemplary scientific rigour, honesty, dignity and collegiality made him a role model to emulate in the heat of today’s politically charged science debates.
His wife, Joan, whom he married in 1952, their children, Ingrid and Jeffrey, and two grandchildren survive him.
Frank Sherwood Rowland, born June 28th, 1927; died March 10th, 2012